A silicogermanate with 20-ring channels directed by a simple quaternary ammonium cation
作者:Jie Su、Yingxia Wang、Jianhua Lin、Jie Liang、Junliang Sun、Xiaodong Zou
DOI:10.1039/c2dt32231e
日期:——
A silicogermanate, PKU-12, with the –CLO type of zeolite framework was hydrothermally synthesized under fluoride media using diisopropylethylmethylammonium as a structure directing agent. The formation of the silicogermanate zeolite with 20-ring channels has not only extended the –CLO family from phosphates into silicogermanates, but also demonstrated its structural diversity.
Quaternary ammonium ions can externally block voltage-gated K+ channels. Establishing a theoretical and experimental model that predicts KDs and the selectivity of K+ over Na+ ions
作者:M.F Wempe
DOI:10.1016/s0022-2860(00)00774-2
日期:2001.5
The physicochemical basis for the high ion selectivity of potassium channels is poorly understood. In the present studies, external blockade of cloned voltage-gated potassium channels with alkyl quaternary ammonium ions are analyzed from a model derived from theory and experimental data. Atomic mass units, electrostatic potential residing on the nitrogen atom, the COSMO van der Waals solvent accessible surface, the Onsager solvation model, and the isodensity PCM solvation model are computed at the semi-empirical and the ab initio levels of theory. A structure-activity relationship (SAR) exists between the calculated values and the experimentally obtained K-D (mM). The SAR model gives us K-D predictions and when K+ and Na+ are incorporated into the model, it dramatically predicts the selectivity of K+ over Na+ ions. (C) 2001 Elsevier Science B.V. All rights reserved.